Vented cover assembly with filter insert for fluid reservoir

Abstract

A vented cover assembly for a hydraulic fluid reservoir comprising a socket ring mountable in a large opening of the reservoir wall, a filter casing attachable to the socket ring by means of a first bayonet lock, and a cap attachable to the filter casing by means of a second bayonet lock, following insertion of a filter cartridge into the filter casing. The second bayonet lock has a higher release resistance than the first bayonet lock, for the removal of the filter casing, filter cartridge and cap from the socket ring as a closed filter subassembly. Air flowing into or out of the fluid reservoir is strained by the filter cartridge.

I claim the following: 
     
       1. A vented cover assembly adapted for attachment to an aperture in a wall of a fluid reservoir, so as to close the aperture while allowing filtered air to pass into and out of the fluid reservoir, the cover assembly comprising in combination: a socket ring adapted for clamping attachment to the edge of said aperture, the socket ring including a tubular wall portion defining a substantially cylindrical bore of a diameter which is smaller than the width of the aperture, the axis of said bore being oriented substantially perpendicular to the reservoir wall and defining a rotational center axis for the cover assembly;   a generally pot-shaped filter casing having a bottom wall and a adjoining substantially cylindrical side wall cooperating with the bore of the socket ring so as to be insertable therethrough and to extend to the inside of the fluid reservoir, with the bottom wall located at the inner axial end of the side wall;   first bayonet-type locking means defined between the socket ring and the filter casing, for the removable attachment of the filter caisng to the socket ring;   a removable cap at the axially outer end of the filter casing;   second bayonet-type locking means defined between the filter casing and the cap for the removable attachment of the cap to the filter casing; and   a filter cartridge arranged inside the filter casing and positioned between the bottom wall of the filter casing and the removable cap, the filter cartridge having an air-permeable filter wall; and wherein   the filter casing has in one of its walls a vent opening for the flow of air between the inside of the fluid reservoir and one side of the filter wall ofthe filter cartridge, and the cap has a vent opening for the flow of air between the outside of the fluid reservoir and the other side of said filter wall.   
     
     
       2. A vented cover assembly as defined in claim 1, wherein the filter cartridge is of annular shape, its filter wall being a substantially cylindrical wall extending substantially concentrically with the side wall of the filter casing;   the filter cartridge further includes an inner end disc at the inner axial extremity of the filter wall and an outer end disc of the outer extremity of the filter wall, the two end discs being of resiliently deformable material;   the bottom wall of the filter casing forms an inner sealing lip engaging the inner end disc of the filter cartridge, and the cap forms an outer sealing lip engaging the outer end disc of the filter cartridge; and   the vent opening of the filter casing is arranged in the bottom wall of the filter casing, radially inside its inner sealing lip, and the vent opening of the cap is arranged radially outside its outer sealing lip.   
     
     
       3. A vented cover assembly as defined in claim 2, wherein the filter cartridge further includes, on the inside of its side wall, a plurality of positioning ribs having axially extending length portions which cooperate with the inner end disc of the filter cartridge to radially position the filter wall at a distance from said side wall.   
     
     
       4. A vented cover assembly as defined in claim 3, wherein the positioning ribs of the filter cartridge are of angular shape, including radially extending rib portions adjoining the bottom wall of the filter casing, so as to reinforce said wall.   
     
     
       5. A vented cover assembly as defined in claim 1 wherein the first bayonet-type locking means includes a plurality of angularly regularly spaced socket members on the tubular wall portion of the socket ring, the socket members being in the form of circumferentially aligned sectoral formations which protrude radially inwardly from said bore, each socket member having an axially facing seating portion;   the first bayonet-type locking means further includes a matching plurality of angularly regularly spaced insertion members on the side wall of the filter casing, the insertion members being in the form of circumferentially aligned sectoral formations which protrude radially outwardly from said side wall, each insertion member having an axially outwardly facing seating portion;   the socket members of the socket ring define insertion gaps between their sector formations through which the insertion members of the filter casing move axially past the socket members, when the filter casing is inserted through the socket ring; and   the first locking means further includes means for axially abutting the filter casing against the socket ring in the insertion sense, in a position in which the insertion members of the filter casing are located axially inside of the socket members of the socket ring and the respective seating portions of the insertion members and of the socket members are in substantial axial alignment, for engagement against each other, under an engagement rotation of the filter casing relative to the socket ring.   
     
     
       6. A vented cover assembly as defined in claim 5, wherein the socket ring includes an axially outwardly facing outer face; and   the means for axially abutting the filter casing against the socket ring includes a radially outwardly extending rim formation on the outer axial extremity of the filter casing, the rim formation abutting against the outer face of the socket ring.   
     
     
       7. A vented cover assembly as defined in claim 6, wherein the tubular wall portion of the socket ring extends into the aperture in the wall of the fluid reservoir, the socket members of the socket ring being located, in the axial sense, in the vicinity of a plane defined by said reservoir wall; and   a major portion of the axial extent of the filter casing is located on the inner side of the reservoir wall.   
     
     
       8. A vented cover assembly as defined in claim 5, wherein each socket member includes, in angular succession in the sense of engagement rotation, an axially inwardly facing ramp portion and a detent ridge at the high end of the ramp portion adjoined by said seating portion, the seating portion being axially recessed from the detent ridge.   
     
     
       9. A vented cover assembly as defined in claim 8, wherein the first locking means further includes an engagement stop for angularly positioning the filter casing relative to the socket ring in a position in which said seating portions are engaged against each other, the engagement stop being in the form of an axially inwardly extending protrusion on at least one of the socket member of the socket ring, arranged to rotationally abut against an insertion member of the filter casing in said engaged position.   
     
     
       10. A vented cover assembly as defined in claim 1, wherein the second bayonet-type locking means includes a plurality of angularly spaced socket members on the side wall of the filter casing, near its out axial extremity, the socket members being in the form of circumferentially aligned sectoral formations which protrude radially outwardly from said side wall, each socket member having an axially inwardly facing seating portion;   the removable cap includes, at a diameter which is larger than the diameter of the filter casing, a substantially cylindrical wall portion with an end face which is oriented axially inwardly;   the second bayonet-type locking means further includes a matching plurality of angularly regularly spaced insertion members on the cylindrical wall portion of the cap, the insertion members being in the form of circumferentially aligned sectoral formations which protrude radially inwardly from said wall portion, each insertion member having an axially outwardly facing seating portion;   the socket members of the filter casing define insertion gaps between their sectoral formations through which the insertion members of the cap move axially past the socket members, when the cap is inserted over the filter casing; and   the second locking means further includes means for axially abutting the cap against the filter casing in the insertion sense, in a position in which the insertion members of the cap are located axially inside of the socket members of the filter casing and the respective seating portions of the insertion members and of the socket members are in substantial axial alignment, for engagement against each other, under an engagement rotation of the cap relative to the filter casing.   
     
     
       11. A vented cover assembly as defined in claim 10, wherein the filter cartridge is arranged to be axially clamped between the bottom wall of the filter casing and the cap, thereby serving as the means for axially abutting the cap against the filter casing.   
     
     
       12. A vented cover assembly as defined in claim 10, wherein each socket member includes, in angular succession in the sense of engagement rotation, an axially inwardly facing ramp portion and a detent ridge at the high end of the ramp portion adjoined by said seating portion, the seating portion being axially recessed from the detent ridge.   
     
     
       13. A vented cover assembly as defined in claim 12, wherein the second locking means further includes an engagement stop for angularly positioning the cap relative to the filter casing in a position in which said seating portions are engaged against each other, the engagement stop being in the form of axially inwardly extending protrusions on the socket members of the filter casing, arranged to rotationally abut against the insertion members of the cap in said engaged position.   
     
     
       14. A vented cover assembly as defined in claim 13, wherein the socket members of the filter casing form a sectorally interrupted rim at the outer extremity of the filter casing, the interruptions serving as said insertion gaps;   the socket ring includes an axially outwardly facing outer face; and   the axial extent of said protrusions of the engagement stop beyond the seating portions of the socket members of filter casing is slightly less than the axial width of the insertion members of the cap, so that, in the engaged position of the second bayonet locking means, the insertion members abut against the outer face of the socket ring, thereby also serving as said means for abutting the cap against the filter housing.   
     
     
       15. A vented cover assembly as defined in claim 1, wherein both bayonet-type locking means are arranged for rotational engagement in the same rotational sense; and   the second bayonet-type locking means has a higher resistance against rotational disengagement than the first bayonet-type locking means, so that the application of a disengagement torque to the cap will disengage the first bayonet-type locking means, thereby permitting the removal of the filter casing and cap, with the enclosed filter cartridge, as a subassembly, from the socket ring.